Try-Catch and "Continue" - is this possible?

I have a section in my code where I am querying all SQL Server Databases on my network. I am first trying to use a SQL Login to access the SQL Server Instance but if that fails then I want to try connecting using my Windows Credentials. After that if I still can't connect then I want the code to fail and then notify the user.

So I guess what I am asking is how can I loop back from 开发者_运维知识库inside of a Try-Catch block to the line just above the Try-Catch block:

String conxString = @"Data Source=SQLInstance1;User ID=FOO;Password=BAR;";
bool secondTime = false;

using (SqlConnection sqlConx = new SqlConnection(conxString))
     {
         Try{
               sqlConx.Open();
               DataTable tblDatabases = sqlConx.GetSchema("Databases");
               sqlConx.Close();
               secondTime = false;
               Console.WriteLine("SQL Server found!");
         }
         Catch(System.Data.SqlClient.SqlException e){
                if (!secondTime){
                   secondTime = true;
                   conxString = @"Data Source=SQLInstance1; Integrated Security=True;";
                      //Loop back to the using statement to try again with Windows Creds
                {
                 else{
                   Console.WriteLine("SQL Server not found or credentials refused");
                 }
                   //Report Failure to connect to user

         }
         finally{
            //Reset Variable
            secondTime = false;
         }

      }

I would probably go this route:

String conxString = @"Data Source=Instance1;User ID=FOO;Password=BAR;";
//in your main function
if(!TryConnect(conxString))
{
   Console.WriteLine("SQL Creditials failed.  Trying with windows credentials...");
   conxString = "new conn string";
   TryConnect(conxString);
}
..............
//new function outside of your main function
private bool TryConnect(string connString)
{
   using (SqlConnection sqlConx = new SqlConnection(conxString))
     {
         Try{
               sqlConx.Open();
               DataTable tblDatabases = sqlConx.GetSchema("Databases");
               sqlConx.Close();
         }
         Catch(System.Data.SqlClient.SqlException e){
                return false;
         }
         return true;    
      }
}

You can use a for loop combined with break when you succeed:

for (int attempt = 1; attempt <= 2; attempt++)
{
    try
    {
        /* perform attempt */
        var success = TryToConnect();
        if (success)
            break;
    }
    catch (Exception e)
    {
        /* report error */
    }
}

You can also record whether you succeeded, etc. or increase the number of attempts or make the number of attempts configurable.

This blog post (albeit from 2005) shows possible solutions for your problem:

Use Goto

TryLabel:
try
{
    downloadMgr.DownLoadFile("file:///server/file", "c:\\file");
    Console.WriteLine("File successfully downloaded");
}
catch (NetworkException ex)
{
    if (ex.OkToRetry)
        goto TryLabel;
}

Write a Wrapper

public static bool Wrapper(DownloadManager downloadMgr)
{
    try
    {
        downloadMgr.DownLoadFile("file:///server/file", "c:\\file");
        return true;
    }

    catch (NetworkException ex)
    {
        Console.WriteLine("Failed to download file: {0}", ex.Message);
        return (!ex.OkToRetry);
    } 
}

static void Main(string[] args)
{
    while (!Wrapper(downloadMgr)) ;
}